• 한국환경과학회지
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• 제16권2호
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• pp.187-195
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• 2007

Long-term passive diffusive samplers(PDS) have been used to measure $NO_2\;and\;SO_2$ concentrations at 21 sampling sites in Daejeon, Korea during the period of January 2000 - December 2002. The spatial distributions of annual $NO_2\;and\;SO_2$ concentrations were mapped. Average annual $NO_2$ concentration over the sampling period was $28.5{\pm}12.5\;ppb$, ranging from 1.2 to 81.7 ppb. Average annual $SO_2$ concentration over the sampling period was $7.7{\pm}4.8\;ppb$, ranging from 0.6 to 26.8 ppb. On average, $NO_2$ concentration was approximately 5.8%(1.6 ppb) larger in 2002. $SO_2$ concentration was decreased by 13%(1.1 ppb) during the sampling period. The seasonal variation of $NO_2\;and\;SO_2$ concentration was observed with a tendency to be higher in fall and winter. $NO_2\;and\;SO_2$, concentrations measured at different site types(patterns of land use) show significant difference. The observed difference in concentration was associated with difference in emissions of $NO_2$ from motor vehicles and $SO_2$ by non-traffic fuel consumption for heating.

• 한국수자원학회논문집
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• 제33권6호
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• pp.733-744
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• 2000

불확실한 저수지 유입량과 수요량 때문에 최적의 저수지 조작기준은 정량화하기 쉽지 않다. 그렇지만 저수지 조작에 일정 수요를 충족시키면서 모의 발생시킨 유입량 시계열을 반영함으로써 음해 추계적 최적화 접근법을 이용하면 조작기준은 작성 가능하다. 이에 본 연구에서는 한강수계 7개 저수지 계통에 적절하도록 수력발전 최대화를 선형추적으로 모형화하고 최적제어를 이용하여 최적조작을 수행하였다. 이 때 2001년 수도권 용수수요를 만족시키도록 한 최적 조작 모형에는 다지점 마코브 모형에 의해 모의 발생된 유입량 자료가 입력된다. 그리고 최적 결과에 대하여 회구 분석과 통계 분석을 수행하여 월별 조작기준을 작성하고 계절별 저수위별 확률을 제시하였다. 이때 상대적으로 저수용량이 커서 조절능력이 좋은 화천댐, 소양강댐, 충주댐은 저류와 방류의 회귀 관계가 잘 형성되었다. 작성된 조작기준으로 실제 운영 기간동안에 대하여 모의조작을 수행하여 그 효율성을 검증하였다.

• 한국약용작물학회지
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• 제13권3호
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• pp.101-104
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• 2005

2003년 6, 8월에 지리산과 전남 담양군의 병풍산에서 자생하는 고추나물과 물레나물을 채집하여 TLC 분석을 하고, TLC-densitometry를 이용해 정량한 결과, 물레나물에서는 hypericin이 확인되지 않은 반면, 고추나물의 꽃봉오리와 잎에서는 다량의 hyepricin이 확인되었다. 그리고 지리산에 자생하는 고추나물보다 병풍산 고추나물의 hypericin함량이 더 높게 나타났고, 고도가 낮을수록 hypericin 함량이 높은 것으로 나타났다. 채집 시기별로 비교했을 때, 병풍산은 6월보다 7월에서 hypericin함량이 높게 나타났고, 지리산에서는 7월에 가장 진하게 보였다. St. John's wort와 고추나물을 비교하였을 때, 2.22 $mg/{\ell}$ hypericin을 함유한 St. John's wort 보다 3.2 $mg/{\ell}$의 함량을 보이는 병풍산 고추나물에서 hypericin함량이 더 높은 것으로 확인되었다.

• 한국환경복원기술학회지
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• 제2권2호
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• pp.53-61
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• 1999

This study was conducted to determine the optimal collecting time and methods of utilization of forest topsoil as a seed-bank source for revegetation materials of slopes. From April to November of 1998, nursery seedbeds in the greenhouse of Seoul National University were seeded with mixtures of forest topsoil and seeds. The nursery seedbeds were treated to evaluate the effect of depths of forest topsoil and seeding amounts. Seasonal experiments with $3{\times}3$ factorial design were conducted in April, June and August. More than 40 seedlings/$m^2$ were observed as the naturally-emerged species in the plot, treated with the top-layer forest soil within the depth of 10cm. However, it was found, as seeding more seeds, the number of appearance of the naturally-emerged species reduced because of the heavy competition between the seeded and the naturally-emerged. According to the results of this research, it is recommended that seeding amount should be no more than 1,000 seeds/$m^2$ to avoid the severe competition. Also it was observed that the forest topsoil collected in spring(April) is better than that collected in summer. The more species of the naturally-emerged were found in the forest topsoil collected in spring. Forest-topsoil-mixed-materials as a seed-bank source could significantly increase the plant diversity and productivity. Effective use of forest topsoil as a seed-bank source may become a valuable tool in future restoration of disturbed slopes for promoting plant community diversity and recycling of spoiled-soils from the slopes.

• BMB Reports
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• 제36권1호
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• pp.1-11
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• 2003

The causative role of polycyclic aromatic hydrocarbons (PAH) in human carcinogenesis is undisputed. Measurements of PAH-DNA adduct levels in easily accessible white blood cells therefore represent useful early endpoints in exposure intervention of chemoprevention studies. The successful applicability of DNA adducts as early endpoints depends on several criteria:i.adduct levels in easily accessible surrogate tissues should reflect adduct levels in target-tissues, ii. toxicokinetics and the temporal relevance should be properly defined.iii. sources of inter- and intra-individual variability must be known and controllable, and finally iv. adduct analyses must have advantages as compared to other markers of PAH-exposure. In general, higher DNA adduct levels or a higher proportion of subjects with detectable DNA adduct levels were found in exposed individuals as compared with non-exposed subjects, but saturation may occur at high exposures. Furthermore, DNA adduct levels varied according to changes in exposure, for example smoking cessation resulted in lower DNA adduct levels and adduct levels paralleled seasonal variations of air-pollution. Intra-individual variation during continuous exposure was low over a short period of time (weeks), but varied significantly when longer time periods (months) were investigated. Inter-individual variation is currently only partly explained by genetic polymorphisms in genes involved in PAH-metabolism and deserves further investigation. DNA adduct measurement may have three advantages over traditional exposure assessment: i. they can smooth the extreme variability in exposure which is typical for environmental toxicants and may integrate exposure over a longer period of time. Therefore, DNA adduct assessment may reduce the monitoring effort. ii. Biological monitoring of DNA adducts accounts for all exposure routes. iii. DNA adducts may account for inter-individual differences in uptake, elimination, distribution, metabolism and repair amongst exposed individuals. In conclusion, there is now a sufficiently large scientific basis to justify the application of DNA adduct measurement as biomarkers in exposure assessment and intervention studies. Their use in risk-assessment, however, requires further investigation.

• Journal of the korean society of oceanography
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• 제32권1호
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• pp.28-37
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• 1997

Two marine bivalve shells were collected from the eastern and western coastal regions of Korea, respectively. Stable oxygen and carbon isotope profiles are constructed using the incremental sampling along the axis of maximum growth to provide the continuous ${\delta}^{18}$O and ${\delta}^{13}$C records, which register the physical, biological and chemical properties of seawater where the organisms live. Cycles in the ${\delta}^{18}$O profiles are interpreted as annual along with the identification of annual growth bands; the maximum ${\delta}^{18}$O values correspond with the coldest temperature of seawater whereas the minimum ${\delta}^{18}$O values with the warmest temperature. The primary control on the amplitude of the ${\delta}^{18}$O profiles is seasonal variation of seawater temperature. The offset of the baseline between ${\delta}^{18}$O values of the two specimens is attributed to differences in both temperature and seawater ${\delta}^{18}$O values between two localities. The ${\delta}^{13}$C profiles show the similar seasonality of carbon cycling associated with phytoplankton productivity. The offset in the ${\delta}^{13}$C profiles between two specimens may be, as in the case of oxygen isotope profile, attributed to the different ${\delta}^{13}$C value of the seawater DIC (dissolved inorganic carbon) between the western coast and the eastern coast. Relationships between the shell isotopic composition and the coastal water properties of shell growth are readily interpreted from the ${\delta}^{18}$O-${\delta}^{13}$C pair diagram of the shell isotope data, similar to the use of salinity-${\delta}^{18}$O diagram for identifying water masses. The preliminary stable isotope results of this study suggest that mollusk shell isotope geochemistry may be useful to monitor the properties of water masses in the coastal and inner shelf setting around Korea and improve the interpretation of paleoceanography, provided the fossil mollusks are well preserved.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.439-442
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• 1999

It is important to analyze the seasonal change profiles of land cover type in large scale for establishing preservation strategy and environmental monitoring. Because the NOAA-AVHRR data sets provide global data with high temporal resolution, it is suitable for the land cover classification of the large area. The objectives of this study were to classify land cover of Korea, to investigate the phenological profiles of land cover. The NOAA-AVHRR data from Jan. 1998 to Dec. 1998 were received by Korea Ocean Research & Development Institute(KORDI) and were used for this study. The NDVI data were produced from this data. And monthly maximum value composite data were made for reducing cloud effect and temporal classification. And the data were classified using the method of supervised classification. To label the land cover classes, they were classified again using generalized vegetation map and Landsat-TM classified image. And the profiles of each class was analyzed according to each month. Results of this study can be summarized as follows. First, it was verified that the use of vegetation map and TM classified map was available to obtain the temporal class labeling with NOAA-AVHRR. Second, phenological characteristics of plant communities of Korea using NOAA-AVHRR was identified. Third, NDVI of North Korea is lower on Summer than that of South Korea. And finally, Forest cover is higher than another cover types. Broadleaf forest is highest on may. Outline of covertype profiles was investigated.

• 한국환경과학회지
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• 제15권7호
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• pp.623-634
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• 2006

In this study, characteristics of fog at Mokpo as the west coastal area of Jeonnam were investigated, using statistical analysis of observed fog and meteorological data. Higher frequency of the fog occurrence at Mokpo was showed in spring(32%) and summer(34%) due to the seasonal high atmospheric pressure. Regional characteristics as radiation cooling, advection of fog and water vapor from surrounding sea and Yeongsan lake, and frontal fog had major effect on the coastal fog at Mokpo on the meteorological conditions of north-west/south wind and calm($0{\sim}2m/s$). Also, as the results of analyzing data of before and after the construction of Yeongsan dam, the frequency of annual mean fog days increased 41 %, specially increased 178% in autumn. The increase of fog days mainly resulted from evaporation during colder seasons and from temperature inversion during warmer seasons over the water surface of Yeongsan lake. The construction of Yeongsan dam had a little effect on the meteorological conditions concerning fog occurrence, because Yeongsan dam which only supplies the water for use do not always carry out outlet of the cold water. In addition, the sea fog at Heuksando located in offshore had not effect on the occurrence of fog at Mokpo.

• 대기
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• 제19권3호
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• pp.227-235
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• 2009

Global climate warming induced by long-lived greenhouse gases is expected to cause increases in wildfire frequencies and intensity in boreal forest regions of mid- and high-latitudes in the future. Siberian forest fires are one of important sources for air pollutants such as ozone and aerosols over East Asia. Thus an accurate quantification of forest fire influences on air quality is crucial, in particular considering its higher occurrences expected under the future warming climate conditions. We here use the 3-D global chemical transport model (GEOS-Chem) with the satellite constrained fire emissions to quantify Siberian fire effects on ozone concentrations in East Asia. Our focus is mainly on spring 2003 when the largest fires occurred over Siberia in the past decade. We first evaluated the model by comparing to the EANET observations. The model reproduced observed ozone concentrations in spring 2003 with the high $R^2$ of 0.77 but slightly underestimated by 20%. Enhancements in seasonal mean ozone concentrations were estimated from the difference in simulations with and without Siberian fires and amounted up to 24 ppbv over Siberia. Effects of Siberian fires also resulted in 3-10 ppbv incresases in Korea and Japan. These increases account for about 5-15% of the ozone air quality standard of 60 ppbv in Korea, indicating a significant effect of Siberian fires on ozone concentrations. We found however that possible changes in regional meteorology due to Siberian fires may also affect air quality. Further study on the interaction between regional air quality and meteorology is necessary in the future.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.40-43
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• 2006

Public demand for the heat pump system as a next generation energy equipment is increasing for its eco-friendly and cost-effective advantage. Many researches have been concentrated on how to calculate and develop its own efficiency, while the possible effect of the heat pump operation on the whole subsurface temperature distribution is relatively less considered, During the current study, subsurface temperature disturbance caused by seasonal surface temperature cycle in Busan area and general W-tube heat pump operation is simulated in 3-dimensional heterogeneous medium. It shows that subsurface deeper than 10m from the surface remains nearly unchanged throughout the 4 seasons and groundwater convect ion in highly permeable layer near the surface acts like a main path of heat plume from heat pump system, This implies the significance of detail descript ion in shallow sedimentary layer or highly permeable layer which plays an important role on the regional flow advection and heat transfer. Also, the effect of groundwater convection increases when the arrangement of the 2 injection pipes and 2 extract ion well is maintained parallel to groundwater flow. Therefore, more careful and detail investigation is required before installation and operation of heat pump system that it may not cause any possible change of microbial ecosystem in the shallow subsurface environment or 'contamination of temperature' for groundwater use as well as the loss of efficiency of the equipment itself. This can also help to design the optimized grouting system for heat pump.